1. Field of the Invention
The present invention is related to an optical module, a host board, and a method of manufacturing the host board.
2. Description of Related Art
FIG. 6 shows a configuration of a host board related to the present invention.
In general, an optical transceiver module 10 includes an optical module 1 encompassing a laser diode (LD) 2 and an avalanche photo diode (APD) 3, a control circuit 5, an LD driving circuit (Laser Driver) 6, an APD driving circuit (boost-up circuit) 7, an amplifying circuit (AMP) or the like.
The optical transceiver module 10 includes a circuit (a first control circuit) 5 that compensates for temperature properties of the LD 2 and APD 3. The transceiver module 10 has been adjusted so that desired properties may be attained by obtaining the temperature properties previously.
A user can perform electrical-to-optical conversion only by mounting the optical transceiver module 10 on a HOST BOARD (hereinafter, referred to as “host board”) 8 and inputting an electrical signal from a control/driving circuit (a second control circuit) 9 located on the host board to the optical transceiver module 10, and therefore, optical elements, such as LD 2 or APD 3, might be handled very easily. And, the LD 2 and APD 3, properties of which greatly vary with temperature, may be controlled by the control circuit 5 embedded in the optical transceiver module 10, therefore users are allowed to be free from concerns about temperature properties of the LD 2 and APD 3. Accordingly, it has been a general configuration upon usage of an optical module 1 according to the related art that the optical module 1 is previously mounted in the optical transceiver module 10.
An example of a device including such an optical module includes: a low-cost optical transmitter (for example, see WO 2002/069464) that can control with high accuracy a variation in optical output properties of semiconductor light emitting elements due to such as change in temperature; an APD bias voltage control circuit (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2002-84235) that allows for a general combination of an light receiving module and an APD bias voltage controller so that the APD bias voltage controller may be provided outside the light receiving module, thus making the light receiving module smaller and a PIN element light receiving module configured together with the light receiving module; and an optical transmitter module (for example, see JP-A No. 2006-156808) that can be effectively manufactured.
The optical transceiver modules listed above have an advantage of being capable of packaging their functions in one hand, but they, in the other hand, also have a disadvantage of difficulty in cost saving due to following reasons:
Firstly, the number of parts is difficult to reduce,
Secondly, the number of equipment required to adjust and test the optical transceiver module 10 is difficult to reduce, and
Finally, the number of man-hours required to adjust and test the optical transceiver module 10 is difficult to reduce.